SignalScopePage » History » Revision 6
Revision 5 (max, 04/22/2017 04:04 PM) → Revision 6/30 (max, 04/22/2017 04:04 PM)
= Signal Scope = == Installation == Before running the scope app, check that the following standard pre-requisite packages are also installed: * GNU Radio * The op25 blocks * Frank's gr-fsk4 block * The op25 repeater block The Python Numeric package is now also required. If you're running Debian or Ubuntu: {{{ apt-get install python-numeric }}} Other than these pre-reqs, pre-requisites, no special setup or installation is needed. There are three overall options or modes depending on your hardware; these are * USRP * External receiver with discriminator tap connected to sound card * External receiver with IF in the audio sound card range (e.g., 24 KHz), referred to as "audio IF" == Running with the disc-tap option == The signal scope does not require the USRP. If you have a discriminator-tapped receiver, use the "-a" option: {{{ ./scope.py -a -v 25 -g 50 }}} == Running with the USRP == It's helpful to find out the current calibration error beforehand (I use kalibrate), for example, +1234 hertz: {{{ ./scope.py -f 412.34e6 -RA -g 65 -c 1234 -v 25 }}} == Running in the Audio IF mode == Receivers equipped with an IF output in the sound card range can be used. This is known as "audio IF" mode. A soundcard sampling rate of 96K is used and the IF frequency (typically 24 KHz) is given using the {{{--calibration}}} parameter: {{{ ./scope.py -A -c 24e3 -g 50 -v 25 }}} == Feature overview == * Spectrum plot * Baseband oscilloscope * Eye Pattern Diagram (Datascope) display supporting several standard symbol rates * Constellation Diagrams * Demodulated Symbol Output * Correlation (including Fast Auto-Correlation) * Direct-frequency entry, signal gain and fine-tuning controls * User-selectable demodulator (FSK4 or QPSK) In the USRP and audio-IF modes, several additional program functions are enabled (spectrum FFT, constellation diagram, PSK demod, and iDEN correlation). In all modes, the {{{--wireshark}}} option is used to write received P25 packet data to Wireshark. == Spectrum Display == [[Image(a.png)]] The controls arranged along the bottom of the page are: * Frequency: to retune, type the new frequency here and press ENTER * Signal Gain: adjusts the baseband (demodulated) signal level * Fine Tune: adjusts tuning frequency over +/- 3000 Hz range * Demod: Selects demodulator (currently used in Demodulated Symbols only) Except for the signal gain control, these controls are only available in USRP RX mode. == Eye Pattern Diagrams == The scope input source can be connected either before or after the symbol filter using the Viewpoint toggle. Also the proper speed must be selected from the available options. [[Image(b.png)]] == Constellation Diagram == [[Image(c.png)]] == Demodulated Symbols == [[Image(d.png)]] == Correlation == [[Image(e.png)]]
